نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی کارشناسی ارشد، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز
2 استاد گروه سازه های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
One of the common ways for bank protection against erosion along rivers’ bends is spur dike
application. Spur dike changes the flow pattern and diverts it towards the river centerline and as a
result protect the river bank from erosion. However, a new flow pattern is formed with higher
velocities and this phenomenon causes the local scour around the structure nose to be increased. The
length of spur dike is one of the important parameters affecting the local scour around the structure.
In order to investigate the effect of the permeable spur length (permeability was 33%) on local scour,
experiments were conducted in a rectangular laboratory flume with a mild 90 degree bend (R/B=4;
where R=radius and B=flume width). In this research a series of spur dikes with three different spur
length including 10.5, 14.0 and 17.5 cm, corresponding to 0.15, 0.2 and 0.25 of flume width,
respectively, was installed along the bend for each experiment. Four Froude number values including
0.21, 0.23, 0.26 and 0.28 with a constant flow depth of 14cm under clear water condition were applied
for each spur length. The results show that the maximum scour depth increased with increasing the
spur length for a constant Froude number; so that the maximum scour depth was happened for the
length of 17.5cm with a Froude number of 0.28, which was 10.71% and 42.86% more than the spurs
with 14.0m and 10.5cm length, respectively. The maximum local scour was observed to happen at
the end part of the outer bank of the bend. It was generally found that with increasing Froude number
and the spur length the scour hole dimensions increased.
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